code: def start_server(
      cluster_spec, job_name: str, task_index: int, cpu_device_num: int
  ):
      """
      Start a TensorFlow server.
  
      Args:
          cluster_spec (dict): TensorFlow ClusterSpec dict
          job_name: TensorFlow job name
          task_index: TensorFlow task index
          cpu_device_num: The number of CPU devices
      """
      s = gen_server(cluster_spec, job_name, task_index, cpu_device_num)
      s.join()
  
file_path: autodist/autodist/utils/server_starter.py
imports: import argparse
  import json
  import os
  import subprocess
  from tensorflow.core.protobuf import config_pb2
  from tensorflow.python.training.server_lib import ClusterSpec, Server
  from autodist.const import DEFAULT_WORKING_DIR, DEFAULT_GROUP_LEADER
  from autodist.utils import logging
label_desc: Use image node_id 3 for calling a global function with example usage: start_server(cluster_spec, job_name, task_index, cpu_device_num) without return types